If he did it, this may be why.

Dr. Bennet Omalu, portrayed by Will Smith in the film, believes that O.J. may have sustained brain damage during his 11-year career in the NFL, which could have played a part in his criminally questionable past.

“I would bet my medical license that he has CTE. Given his profile, I think it’s not an irresponsible conclusion to suspect he has CTE,” Dr. Omalu told PEOPLE.

CTE, or Chronic Traumatic Encephalopathy, is a degenerative brain disease usually found in athletes with a history of repetitive brain trauma. The NY Daily News says that Simpson considered using CTE as part of his defense during his armed robbery and kidnapping case in 2008, but not during the infamous 1995 Nicole Brown Simpson and Ronald Goldman murder trial.

PEOPLE also reports that O.J. was rumored to have one of the biggest heads in the NFL. To which Dr. Omalu says, “If you have a bigger head that means your head is heavier. That means the momentum of your impact would be bigger. It’s basic physics.”

O.J. Simpson is currently serving a 33-year sentence in a Nevada prison.